Solar panel assemblies having photovoltaic (PV) cells arrayed over a large surface area directly exposed to the sun are known. However, PV cell material is expensive and solutions have been sought to reduce the amount of PV cell material required in solar panels. One of these solutions makes use of concentrating optical elements, such as lenses and mirrors, to concentrate sunlight on a smaller surface area occupied by a correspondingly smaller PV cell. Given that the concentrating optical elements all have a non-zero focal length, they make for concentrated photovoltaic (CPV) modules that are typically bulkier than their non-concentrating counterparts. This bulkiness is disadvantageous not only in terms of the handling of the CPV modules, but also in terms of material costs. It is possible to obtain less bulky CPV modules while maintaining the same concentration factor by reducing the size of the PV cell; however, dicing PV cells into smaller cells increases the complexity and cost of the modules.
Additionally, present CPV modules typically require that the concentrating optical elements be secured in a complex structural enclosure to hold all the elements in place. This invariably adds to the weight and cost of the CPV modules, and makes for either stricter shipping requirements to mitigate risk of breakage of the assembled CPV modules, or requires that the CPV modules be shipped disassembled to their destination, thereby requiring assembly time and effort at the receiving destination. Reference is made in this regard to EP 2077586 and EP 2194584 where a Fresnel Lens focuses the light onto a an optical part that mixes the light without changing the direction of the sun light and this optical part slightly increases the acceptance angle.
Solar concentrators using optical fibres and branched waveguides have been disclosed that use flat light-guides (or waveguides) based on TIR to further reduce the overall size. They don't show a secondary optical element to change the direction of the sun light and to further concentrate the sun light onto a photovoltaic (PV) cell to increase the efficiency, add concentration and allow the PV cell to be aligned with respect to the waveguide. Reference is made in this regard to U.S. Pat. No. 3,780,722 and U.S. Pat. No. 6,730,840.
More recently advances on the compact light-guide (waveguide) TIR based solar concentrators where the TIR waveguides are optically coupled to thinner, more compact and easier to make, to couple and to assembly collecting, redirecting and focusing optical elements. Reference is made in this regard to WO 2008/131561 to John Paul Morgan, WO 2009/035986 to Ghosh and to WO 2009/063416. In these patents the optical efficiency depends on the relative position between several optical components and these patents don't show solutions to retain and align all these components.
Further improvements in the latest compact CPV modules are therefore desirable.